The present invention relates generally to protection switching in a network, and more particularly to a method and system for automatic line protection switching of embedded channels.
With the move toward decentralized processing, users have interconnected workstations, computers and other types of local equipment through local area networks (LANs). More recently, as users move toward global communications that allow equipment to appear as if it were attached to the local area network, local area networks have been interconnected through wide area networks (WANs).
Frame relay is a packet-switching protocol used in wide area networks that has become popular for interconnection of remote local area networks. The packets are in the form of frames which are variable in length. The key advantage to this approach is that a frame relay network can accommodate data packets of various sizes associated with virtually any native data protocol. Thus, a frame relay network is completely protocol independent because it does not undertake a lengthy protocol conversion process. In this way, frame relay offers faster and less-expensive switching between local area networks.
Private virtual channels (PVC) have been defined within backbone trunks of frame relay networks to provide what appears to be dedicated lines without the cost associated with a dedicated line. Because the trunks are shared among all users of the frame relay network, however, protection switching is not independently provided for the private virtual channels. In addition, transmission on the private virtual channels is subject to congestion protocols and may be prohibited in times of high congestion. As a result, private virtual channels are not robust and are unsuitable for applications requiring reliable communications.
In accordance with the present invention, an automatic line protection switching method and system for embedded channels are provided that substantially eliminate or reduce disadvantages or problems associated with previously developed systems and methods. In particular, the present invention provides an automatic protection switching system and method that switches embedded channels, such as private virtual channels (PVC), independently of backbone trunks.
In one embodiment of the present invention, a communications network includes a transmit node and a receive node. A first transmission line extends between the transmit and receive nodes and includes a primary embedded channel for carrying channel traffic between the nodes and normal operation. A second transmission line extends between the transmit and receive nodes and includes a secondary embedded channel for carrying the channel traffic between the nodes in the event of a fault condition on the primary embedded channel. The transmit node is operable to automatically switch transmission of the channel traffic from the primary embedded channel to the secondary embedded channel in response to a fault condition being detected in the primary embedded channel at the transmit node. The receive node is operable to automatically switch reception of the channel traffic from the primary embedded channel to the secondary embedded channel in response to detection of the same fault in the primary embedded channel by the receive node.
More specifically, in accordance with a particular embodiment of the present invention, the transmit and receive nodes are routers that monitor the transmission lines and embedded channels, the transmission lines are network trunks and the embedded channels are private virtual channels defined within the network trunks. In this and other embodiments, the fault condition may be a bit error rate of the primary channel below 10xe2x88x926.
The transmit and receive nodes may each be further operable to independently monitor the primary embedded channel for a non fault condition and to automatically switch transmission or reception of channel traffic from the secondary embedded channel to the primary embedded channel in response to the non fault condition. The non fault condition may be a bit error rate of the primary channel above 10xe2x88x924.
Technical advantages of the present invention include providing automatic line protection switching for embedded channels in a communications network. In particular, protection switching is provided for the embedded channel independent of the trunk transmission line. This is accomplished by independently monitoring and switching between primary and secondary embedded channels at each end of the embedded channel in response to a same fault condition. As a result, a robust management or other network requiring high reliability may be created using embedded channels.
Other technical advantages of the present invention will be readily apparent to one skilled in the art from the following figures, descriptions, and claims.